In alignment with Healthy People 2010 (Arthritis/Osteoporosis) and research objectives established by the NIAMS, the overall goal of this study is to prevent illness and disability related to arthritis and osteoporosis. This study will develop a marrow population of mesenchymal cells (MSCs) that are very small and have embryonic-like properties (VSEL cells). This study will develop MSCs for true regenerative medicine. We hypothesize that human VSEL cells represent true MSC cells that can be utilized for osseous regeneration - and ultimately for the treatment of osteoporosis. The aim of this study is to test in vivo the capacity of human VSEL cells to form bone in an animal model. The goals and objectives of this study are closely aligned with the official NIH position regarding stem cell research: to examine stem cells as a renewable source of replacement cells to treat diseases, conditions, and disabilities. PUBLIC HEALTH RELEVANCE: NeoStem will conduct research on stem cells and explore their enormous promise to produce breakthrough therapies and cures. The study will investigate the effect of a marrow population of mesenchymal cells (MSCs) that are very small and have embryonic-like properties (VSEL cells) that can be utilized for bone regeneration - and ultimately for the treatment of osteoporosis. This study will test in vivo the capacity of human VSEL cells to form bone in an animal model and regenerate a critical sized boney defect.